From DNA To Proteins: Transcription Flashcards
Pre-messenger RNA (pre-mRNA)
The immediate products of transcription in eukaryotic cells. These are modified after transcription to become mRNA.
Ribosomal RNA (rRNA)
RNA molecule that is a structural component of the ribosome.
Ribozyme
RNA molecule that can act as a biological catalyst.
Messenger RNA (mRNA)
RNA molecule that carries the coding instructions for a polypeptide chain from DNA to a ribosome.
Transfer RNA (tRNA)
RNA molecule that carries an amino acid to the ribosome and transfers it to a growing polypeptide chain in translation.
Transcription Unit
Sequence of nucleotides in DNA that encodes a single RNA molecule and the sequences necessary for its transcription; normally contains a promoter, an RNA-coding sequence, and a terminator.
Requirements Of Transcription
A DNA template containing a promoter, ribonucleotide triphosphates, and RNA polymerase.
Template Strand
The DNA strand that is used as a template during transcription. The RNA synthesized during transcription is complementary and antiparallel to this DNA strand.
Non-Template Strand
The DNA strand that is complementary to the template strand; not used as a template during transcription.
Downstream
Towards the 3’ end.
RNA-Coding Region
Sequence of DNA nucleotides that is copied into an RNA molecule.
Promoter
DNA sequence that the transcription apparatus recognizes and binds to in order to initiate transcription; indicates the direction of transcription, which of the two DNA strands is to be read as the template, and the starting point of transcription.
Terminator
Sequence of DNA nucleotides that terminates transcription.
Upstream
Towards the 5’ end.
Elongation Stage Of Transcription
The addition of nucleotides to the mRNA strand during transcription after initiation.
Initiation Stage Of Transcription
Beginning of transcription and occurs when RNA polymerase binds to the promoter region of a gene.
Transcription Apparatus
Complex of transcription factors, RNA polymerase, and other proteins that assemble on the promoter and are capable of initiating transcription.
Termination Stage Of Transcription
The end of transcription where RNA polymerase releases the DNA template and the newly synthesized RNA.
Core Enzyme
Five subunits of most bacterial RNA polymerases that, during transcription, catalyze the elongation of the RNA molecule by the addition of RNA nucleotides.
RNA polymerase
Enzyme that synthesizes RNA from a DNA template during transcription.
Sigma Factor
Subunit of bacterial RNA polymerase that allows RNA polymerase to recognize a promoter and initiate transcription.
Holoenzyme
Complex of an enzyme and other protein factors necessary for its complete function
Ribonucleoside triphosphate (rNTP)
Substrate of RNA synthesis; consists of a ribose sugar and a base (a nucleoside) attached to three phosphate groups. In transcription, two of the phosphates are cleaved, producing an RNA nucleotide.
rho-dependent terminator
Sequence in bacterial DNA that requires the presence of the rho factor to terminate transcription.
-10 Consensus Sequence (Pribnow box)
Consensus sequence (TATAAT) found in most bacterial promoters approximately 10 bp upstream of the transcription start site.
-35 Consensus Sequence
Consensus sequence (TTGACA) found in many bacterial promoters approximately 35 bp upstream of the transcription start site.
Consensus Sequence
Sequence that comprises the most commonly encountered nucleotides found at a specific location in DNA or RNA.
rho factor
A protein that binds to bacterial RNA polymerase and facilitates the termination of transcription of some genes.
Hairpin
Secondary structure formed when sequences of nucleotides on the same polynucleotide strand are complementary and pair with each other.
rho-independent termination
A hairpin loop structure and consequent U-rich portion in the transcript are formed to cause the termination.
Polycistronic mRNA
Single RNA molecule transcribed from a group of several genes; uncommon in eukaryotes.
Exon
Coding region of a gene that is interrupted by introns; after transcription and posttranscriptional processing, these remain in mRNA.
Colinearity
Concept of direct correspondence between the nucleotide sequence of a gene and the continuous sequence of amino acids in a protein.
Protein Coding Region
The part of mRNA consisting of the nucleotides that specify the amino acid sequence of a protein.
5’ Untranslated Region
Sequence of nucleotides at the 5’ end of mRNA; does not encode the amino acids of a protein.
Intron
Noncoding sequence between coding regions in a eukaryotic gene; removed from the RNA after transcription.
Shine-Dalgarno Sequence
Consensus sequence found in the bacterial 5’ untranslated region of mRNA; contains the ribosome-binding site.
3’ Untranslated Region
Sequence of nucleotides at the 3’ end of mRNA that is not translated into amino acids; affects the stability of the mRNA and helps regulate the translation of the mRNA protein-coding sequence.
5’ cap
Modified 5’ end of eukaryotic mRNA that plays a role in the binding of the ribosome to mRNA and affects mRNA stability and the removal of introns.
Poly(A) tail
String of adenine nucleotides added to the 3’ end of a eukaryotic mRNA after transcription.
RNA splicing
Process by which introns are removed from RNA and exons are joined together.
5’ splice site
The 5’ end of an intron where cleavage takes place in RNA splicing.
3’ splice site
The 3’ end of an intron where cleavage takes place in RNA splicing.
Branch point
Adenine nucleotide in nuclear pre-mRNA introns that lies upstream of the 3’ splice site.
Spliceosome
Large complex consisting of several RNAs and many proteins that splices protein-encoding pre-mRNA.
Lariat
Loop-like structure created in the splicing of nuclear pre-mRNA when the 5’ end of an intron is attached to the branch point.
Cloverleaf structure
Secondary structure with four major arms common to all tRNAs.
Anticodon
Sequence of three nucleotides in tRNA that pairs with the corresponding codon on mRNA to ensure that the amino acids link in the correct order during translation.
RNA interference (RNAi)
Process in which cleavage of double-stranded RNA produces small RNAs (siRNAs or miRNAs) that bind to mRNAs containing complementary sequences and bring about their cleavage and degradation.
MicroRNA (miRNA)
Small RNA molecules produced by cleavage of double-stranded RNA arising from small hairpins within RNA that is mostly single stranded. The miRNAs combine with proteins to form a complex that binds (imperfectly) to mRNA molecules and inhibits their translation.
Incorrect! Correct answer:Small interfering RNA (siRNA)
Single-stranded RNA molecule produced by the cleavage and processing of double-stranded RNA that binds to complementary sequences in mRNA and brings about the cleavage and degradation of the mRNA. Some bring about changes in chromatin structure.
